Contra-rotating plasma system



May 12, 1964 w. R. BAKER ETAL coNTRA-RoTATING PLASMA SYSTEM 2 Sheets-Sheet 1 Filed Dec. l0, 1962 NVENTORS WILL/AM R. BAKER KLAUS HLBCH BY IMEI ATTORNEY May 12, 1964 w. R. BAKER ETAI.

CONTRA-ROTATING PLASMA SYSTEM 2 Sheets-Sheet 2 Filed Dec, l0, 1962 ATTORNEY v plasma. .is increased and the probability thatV fusion reactions will .v occur between ions is greatly'enhanced.

Y 3,132,996 1 CONTRA-ROTATING PLASMA SYSTE William R. Baker, Orinda, and Klaus Haibach, Berkeley, Calif.; assignors to the United States of America as represented by the United States Atomic Energy Commission Filed Dec. 10, 1962, Ser. No. 243,683

` 14 Claims. (Ci. 176-7) The present invention relates generally to magnetohydrodynamic devices and more particularly to apparatus for forming, containing and heating an ionelectron plasma under conditions productive of a high rate of nuclear Y interactions therein. The objective of many plasma heating devices is to impart suliicient relative velocity to the ions in the plasma that collisions among ions will cause fusion reactions.

' Such fusionV reactions release energy in various forms,

of which energetic neutrons are the most readily utilized 1 atthe present stage of development.

`magnetic mirrorcoils for producing an axially directed magnetic mirror iield therein. 'A radial electric eld is provided,'the inner portion of the electric eld being directed outwardly from theaxis of the machine and the -outer portion being directed radially' inward from the housing. The electric fields thus meet at an annular region approximately halfway between the axis and the housing. This interface where the oppositely directed elec- V"tric -iields meet Will be herein called the heating region.

t United States Patent C ice Patented May 12, 1964 Y. 2 Y orbit where the velocity is highest occurs in the heating region. If the particles were permitted to go into a circular orbit, the particles in the heating region would have a steady-state average velocity much below the 'peak velocity, consequently decreasing the heating rate and the rate of particle reactions. In thev present invention,v if the electric field is retained for a suiiciently long time,

the high relative energy of the particles in the'high velocity portion of the cuspate orbits is thermalized or randomized through collisions. retained if the electric eld is subsequently removed.

The present invention belongs to the class of plasma devices wherein the purity of the plasma is maintained by releasing the un-ionized gas through a fast-actingvalve at a central point within the plasma chamber in a manner similar to that described in U.S. Patent 4No. 3,021,272 issued February 13, 1962 for Plasma Heating and Coniining Device. Alternate valve structures of this type are described in copending U.S. patent applications Serial No. 112,132 for Counter-Rotating Plasma DeviceV filed May 23, 1961, now vlEatent 3,096,269, and Serial' No. 225,169 for Plasma Propulsion Device led September 20, 1962.

In this class of plasma device the neutral gas is released through the fast operating valve at a point remote from the insulators, which are necessarily present if an electric ield is to be provided. The gas is ionized, contained, and heated before gas diffusion to the insulators Ions inthe outer portion of the plasma chamber are .drawninwardly by the electrical iield while ions in the i'anerportion of the plasma chamber of the machine are accelerated outwardly. Owing to the axial magnetic lield, the ions follow an azimuthal path around the axis of the machine while simultaneously exhibiting a cycloidal mtion.- The ions in the inner and outer portions are deected in opposite directions Vso that an ion from the Y` outerV portion of the machine and one from the inner Y portion travel in opposite directions in the heating region. Furthermore, the maximum velocity that the ions which passV into the heatingV region will develop is attained in Y. the heating region. Some of the ions collide and'various interactions, vincluding nuclear fusion reactions, occur.

The relative Velocity of the ions is increased several times over that of the usual rotating plasma devices where the direction of rotation is the same throughoutthe Thus, in the present invention the heating effect -In rotational plasma apparatus such as the'present invention,Y the plasma particles have individual cuspate f orbits Within the plasma body and the entire plasma body may continue to rotate after burn-out, which occurs when 'all the neutral gas particles are ionized., No additional vLarmor energy can be gainedl by the plasma particles` 4from a'D.,C. electric field after burn-out. jin conventional plasma apparatus the electric field may Accordingly,

be eliminated after burn-out. While elimination of the f ,electric iield causes the individual particle orbits to change can occur. The `maximum plasma heating obtainable is enchanced by such a procedure since, if contact of the hot plasma with the insulators should occur,l not only are impurities eroded from the insulators which inhibit further plasma heating, but a higher electric field can be held across the plasma when there is no plasma-insulator contact. By maintaining a pure plasma, as in the present invention, a higher plasma velocity and temperature is obtained and the containment time is lengthened. I l

A further important advantage of this class of device is that the electric and magnetic elds are present either at the time the neutral gas is admitted into the plasma chamber or shortly thereafter. Since the full intensity of electric iield is present during the period when the gas is ionized, the Larmorradius of the particle orbits is larger than it would be in conventional apparatus where ionization occurs during the time the electric ield is being created and has not yet attained full intensity. Ideally, the plasma body will have an energy in rotational velocity at burn-out deiined by the ratio of electric-and magnetic ields, E/B, and an equivalent energy in random phase Larmor motion (or heat) of the ions. Thestability of the plasma is improved `if the ion Larmor radius is large, as discussed by Rosenbluth, Krall and Rostoker in Nuclear Fusion, Supplement 143-50 (1962) (GA-2371). Thus the plasma stability in the class of device including the present invention is. improved over other types of plasma device.

Therefore, it is an object of the present invention to providel a more efficient apparatus for heating an ion-k electronplasma to high temperatures.

It is another object of the present invention to provide ystructure for `utilizing the highmobility of plasma particles along magnetic iieldplines to extend the eliect of remote Velectrodes so that a reversal of electric iield 'direction can be obtained in electrode free regions. v Y lt is 4an object of the presentinvention to provide means for enhancing .the rate at which high velocity particle collisions occurlin a plasma.

It lis another object of the present invention to'provide a means for rotating the outer portion of a plasma body in yone -direction while rotating the` inner porti-on in the mareas Such thermal energy' can then be' i the axis of a magnetohydrodynamic device,

`FIGURE 2 is a cross-sectional view of the plasma heating region in the apparatus of `FIGURE 1 taken at Y line 2-2 thereof, and

FIGURE 3 isa broken 'out view of a second embodiment of the invention. v

Referring now to FlGURBS 1 and 2 in conjunction,

Y there is shown an electrically conductive cylindrical housing 11, which functions as an outer electrode, having llianges 12 and 13 at opposite ends and having an enlarged central portion 14. Cylindrical insulators 16, 17, 118 and 19 have the same diameter as housing 11 and .are each flanged at both ends. The insulators 1d and 17 are secured coaxialiy to each end of housing y11. The cylindrical insulators 18 and 19 are similarly secured to the fianged insulators 16 and 17, the insulators forming an extension of the chamber deiined by lthe housing 11. A pair of conductive closure discs 21 and 22 are secured to the outer anges of insulators 18 and 19 respectively. O-ring seals 23 are provided at the various junctures between the described elements, thus forming aV gas tight chamber within housing 11. v Y

A long tubular center electrode 24 is disposed along the axis of housing 11 between closure discs 21 and 22 and is secured thereto. Atrthe center of the electrode Z4, a plurality of apertures 2o are provided, in an annular band therearound, for the injection of gas into housing 11. A very rapidly acting valve 27, which may be of the type Vdescribedin copending application S.N. 112,132 hereinbefore identified, is disposed within the axial electrode 24 at the apertures 2d. Such valve 2.7 releases a metered quantity of gas 4through the apertures 26 in a very short burst or puff. The Valve 27 is electrically controlled, as described in the above identified copending application, by a control 28 while a gas supply V29 provides a suitable gas or mixture of gases to the valve. Deuterium and tritium are examples of suitable fuel gases. Both the control 28 and gas supply 29 are disposed outside the housing 11 and are` connected with the valve 27 by conduits 31 and 32 respectively which pass through the end of the axial electrode 24.

, 4 disposed coaxially around the housing 11 approximately at the longitudinal positions of the field electrodes 33 and v34 respectively. A magnet current source 44 is connected to the coils 42 and 43 -to provide for similarly directed magnetic elds in `each coil. Owing to the spacing of the coils, a magnetic mirror type field is provided at the central region of the housing, the general shape of the magnetic eld within the housing being indicated in FGURE 1 by iiux lines 46. The configuration of the enlarged VportionV 14 of the housing 11, in general, conforms to the shape of the magnetic mirror field. The iiux surface or magnetic tube of flux is preferably parallel to the field electrodes 33 and 34 at each side of the 4magnetic mirror field. At outermost ends of the coils 42 and 43 the flux lines 46 curve outwardly and intersect with the housing 11, 4near the fianges i12 and 13. The llong slots 38 and 39 are provided so that most of the ux lines 46 within region of the field electrodes 33 and 34 will not intersect such electrodes. s

A vacuum pump 47 is coupled to a pumpout port 48 in the closure disc 22 so that all gases may be removed from the housing 11 prior to operation.

The .two ends of the invention are essentially mirror i images around a 4transverse plane passed through the midas the field electrodes 33 and 34 since the ions and elec- A pair of cylindrical field electrodes 33 and 34 are disposed coaxially around the axial electrode 24, slightly closer -to the axial electrode than to the housing 11, and

`are spaced apart symmetrically on each side of the aper- Iturcs 26. The axial length of field electrodes 33 and 34 is not critical since only the yfacingV portions of the electrodes are lordinarily utilized iu the operation of the in` vention. The outermost ends of the field electrodes 33 4and 34 have flanges 36 and 37 secured between insulatorsl :16 and '18 and between insulators 17 and 19 respectively, thus yelectrically isolating the held electrodes frorn'the housing 11 and the axial electrode 24; A plurality of long, longitudinal slots 38 and 39 are formed along the central portions of each of the field electrodes 33 and 34 respectively, the slots being .spaced -around the circumference thereof. The negativepotential terminal of Y a high'voltage source 41 is connected to the field electrodes 33 and 34 while the positive terminal of the source is connected to the housing 11 and the closure discs 21 and 22. Thus the field `electrodes 33 and 34 are at a negative potential with respect to the housing 11 and axial electrode 24. i v

A pair of spaced apart magnet'coils 42 and 43 lare die of the apertures 26 in the axial electrode 24. For purposes of explanation, the annular space between the facing ends ofthe field electrodes 33 and '34 and between the housing 11 and electrode 24 will be designated the containment region 51. Anannular heating region `52 is defined as the portion of the containment region 51lv which lies `on or is adjacent the surface of revolution of a particular magnetic line 4o which passes through the facing annular end surfaces of field electrodes 33 and 34. The heating region 52 is the location of the interface Y etween the two oppositely rotating bodies which are formed during operation of the invention. Y

The plasma heating reg-ion 52 is at the same potential trodes have very high `mobility along the magnetic field within the containment region S1. -If a different electric charge should tend to develop at any point on the particular'magnetic field yline 46' (plasma heating region 52) that passes through the ends of the field electrodes G3 and 34, plasma particles hav-ing the opposite charge 'immediately flow toward such' point from the electrodes and the charge is negated. Thus the heating region 52 functions as a virtual electrode and charged'particl'es are affected thereby in substantially the same way that particles are affected by a metallic electrode. Since there is only'a limited particle mobility along field lines through magnetic mirrors, magnetic lines which intersect: any'conductors disposed outside the containment region 51 do not readily carry the potential of such conductors to'the inside Vof the region 51.

Considering now the operation ofthe device, assume that air in the interior of the housing 11 is evacuated by the pump 47, that the magnet coils`42 and 43 are energized to create the magnetic mirror field 46', and that the high voltage source 41 is energized.k An outer electric yiield is created inwardly from the housing 11 toward the field electrodes 33 and 34 while an inner field is formed in the opposite direction outwardly from the electrode 24 to the iield electrodes as indicated by arrows 57 lin FIG- URE 2. Owing to the presence of a virtual electrode as described above, the plasma heating region 52 is the region where the electricV field is zero, or in other terms, where the electric field direction reverses. y v f TheY supply 29 provides gas to the valve 27 which is then rapidlyopened by activation of valve control 28.V The neutral Vgas passes outwardly through the apertures 26 ina burst or puff and diffuses outwardly from the apertures 26. As soon as neutral gas particles diffuse to the vicinityof the field electrodes 33 and 34 and to the housing 11, breakdown immediately occurs from the field electrodes to both the axial electrode 24 and housing 11,

` position; potential.

- operatioiiof the device.

Yionizing nearly all thegas particles in the containment region 51. Since there is a negative potential applied to the field electrodes 33 and 34, the positive ions are accelerated along the electric field lines toward the plasma y heating region 52, but owing to the magneticl field 46, the.

ions are defiected into cuspate orbits. Typical ion paths Vare shown in FIGURE 2, the path of a first ion 53 which velocity and following a somewhat cycloidal path while kmoving around the axis of the apparatus and simultaneously moving towards the median transverse plane thereof owing to the magnetic mirror effect. The ion 56 has maximum velocity at'plasma heating region 52 where itis at the portionv of the orbit nearest the electrode 24 Y and hasrpassed' through the maximum amount of electric field. If'no ion collision occurs, thevion continues the substantially cycloidal motion, turning outwardly` toward housing 11 and gradually decelerating until it reverses direction and again accelerates back toward the plasma heating region 52. The ion will continue orbiting inthe described manner until a collisionoccurs. iH yTire-individual cycloidal orbits of both the ions and electrons cause a general rotation of the plasma around the axial electrode 24, theV annular plasma body outside the plasma heating region 52 rotating in one direction and the plasma body on the inside rotating in the opposite direction. Y Since the ions 53 and 54 are traveling in opposite directions at the plasma heating region 52 and as each ion has its maximum velocity when in such region,

an increase is obtained which, for the same electric and magnetic fields, may typically be up to four times the `heating effect of conventional rotating plasma devices.

Since Athe cycloidal orbit of an ion has a much greater Vradius than the orbit of an electron, space charges are produced within the plasma both near the axial electrode 24 and near the housing 11. The ions are defiected toward 'the heating regiony 52 more than are the electrons, thus leaving a net electrical charge caused by the excess of electronsA remaining near the positive electrodes (housing 11 and electrode 24). The voltage 'drop across such space charge region is in opposition to the potential appliedfby 'the high voltage source 41 and is thereforeundesirable since it reduces the electric field intensity across the plasma'. In the present invention, the major portion of `the excess electrons'can be removed to eliminate this op- Electrons are much more Amobile alongmagnetic field lines than are ions, therefore, the

mutual repulsion of excess electrons is sufficient` to cause the electrons to flow through the magnetic mirrors and along the magnetic ylines to the region where such lines intersect the 'housing 11. It is necessary-that the electrons-flow `along magnetic lines to a positive electrode jsuch as' the housing 11, hence the slots 38 and, 39 are provided in the field electrodes 33 and'34 so that the electrons jalong the axial'electrode 24, which are repelled'by the negative charge on the field electrodes, canV pass through the slt's kto Vthe positive housing 11. Thus the space charge Aat the axial electrode 24 and that at the housing 11 isdisrsipated and the full potential of the high Voltage source 41 is applied across the plasma to enhance the .In a typical contra-rotating plasma system of the type y yherein described the electric field may be formed by a 50 kilovolt potential from. the high voltage source 41-while the magnetic field intensity'is approximately 3() kilog'auss in the centralcontainment region 51.' The overall length 'of the,v housing 11 together with insulators 16, 17, 18 and 19 is five feet and the housing has a diameter of nine v 6 of three inches. The use of more intense electric and magnetic fields requirescorresponding increases in the dimensions. f l Y It may be desired in some instances to simplify the above described apparatus by eliminating one of the field electrodes and a portion of the axial electrode. This is possible since as described above, a magnetic lineina containment region which passes through an electrode l1n such region will provide a virtual electrode along the magnetic line if plasma is present to conduct current.

Referring now to FIGURE 3, there is shown a modified device having the simplified structure. Except as will be herein described, the structure and mode of operation of the apparatus of FIGURE 3 is essentially similanto that of -FIGURE 1.- The apparatus comprises a cylindrical conductive housing 61 having outwardly projecting flangesl the magnetic field 66 which is provided by a pair offield coils 67 and 68 disposed coaxially around the housing 61 on each side of the enlarged portion 64. A `fiat conductive closure disc 69is secured to iiange 62 of housing 61. One end 72 of a long,slender, tubular electrode 71 issecured to disc 69 while` the other end 73 projects a short distance into the enlarged portion 64 of the housing -along the axisV thereof.y A rapid acting valve 74 is disposed within end 73 of the electrode 71, the valve having the structure hereinbefore identified. The electrode end 7 3 is partly open so that gas released from the valve 74 is distributed throughout the space within the enlarged portion 64. Y

A terminally flanged cylindrical insulator 76 is secured to flange 63 of housing `61 in coaxial relationship thereto, to isolate the housing electrical-ly from a flat conductive disc 77 Which closes the open end of the linsulator 76. A long cylindrical, conductive field electrode 7Sy-is secured `to the clolsure disc 77 and projects along the axis of housing 61 into the enlarged portion 64 opposite the .axial electrode 71. Tihefield electrode has a. diameter intermediate between that of the housing 61 and the axial electrode 71. Y

As in the previously described embodiment, a direct current high voltage supply 79 is connected from' the closure disc 77 to the housing 61, with .the negative potential applied ,to the disc. A magnet current supply S1 is connected to the magnet coil-s 67 and 68 to provide the magnetic mirror field. A gas supply 82 is connected through .the axial electrode 71 to the valve 74 which is actuated by a valve control 83. A vacuum pump 84 is coupled to a port 86 in the closure disc 69. Y

The operation of the apparatus of FIGURE 3 is essentially similar to that of FIGURE l. Neutral gas is emitted from the end 73 of .the axial electrode 71 by operation of valve 74. A discharge occurs Vthrough the gas and the resultant ions `are accelerated toward a plasma heating region formed along the annular magnetic iiux tube surface 87 which intersects the annular end surface lof field electrode 78. The electric field, indicated by larrows 89, is directed toward the heating region 87 from both the housing `61 and from the magnetic flux region 88 which extends along the axis of the apparatus which flux intersects the' axial electrode 71. The region occupied by the magnetic ux 88 is at the same potential as the axial electrode 71` Yand Ifunctions. effectively as an exten# described previously withregard to FIGURES l and 2 and -a similar plasma heating effect is obtained.

- Many of the aspects of the two described embodiments of the invention can be combined in various ways. The

Aaxial electrode 71 as employed inthe apparatus of FIG- URE 3 may -be utilized with a pair of field electrodes 33 7 and 34 as employed with the iirst embodiment for example.

Thus while the invention has been disclosed with respect to certain exemplary embodiments, it will be apparent to those skilled in the art that numerous variations and modiiications may be made Within the spirit and scope of the invention and it is not intended to limit the invention except as defined in the following claims.

What is 'claimed is:

l. In a magnetoyhdrodynamic apparatus, the combination comprising:

(a) an annular outer electrode,

(b) means providing a magnetic field within said outer electrode which -ield is symmetric about an axis extending longitudinally `through said outerrelectrode and which yforms a plasma trapping region therein,

(c) a centr-al electrode disposed within saidy outer elec- V trode substantially at said axis and projecting into said plasma trapping region,

(d) an annular field electrode Vdisposed Within said outer electrode and encircling said axis in spaced apart relation to said central electrode and said outer electrode,

(e) a high voltage source applying a negative potential to said field electrode relative to that of said outer electrode and said central electrode,

(f) means `for admitting gas to said plasma trappin region and, n Y

(g) means providing for a substantial degree of Vacuum within said plasma trapping region.

2. ln a magneitohydrodynamic device for ionizing a gas and for heating the resulting plasma, the Vcombination comprising:

(a) an electrically conducting annular outer electrode,

(b) means creating a magnetic -ield which field .has a plasma :trapping configuration at aY region within said outer electrode, c

: (c) a center electrode extending into said plasma trapping region,

(d) at least one annular eld electrode projecting into said plasma trapping region at a radial position which'is intermediate between said outer electrode and said center electrode,

(e) a source of electrical potential applying -a iirst 4 potential yto'said outer electrode and saidcenter electrode and applying a second relatively negative potential to said ield electrode thereby creating oppositely directed electric rields from said field electrode to said outer electrode and `from said iield elec-V trode to said center electrode, and f t (f) a valve for injecting gas into said magnetic iield.V 3. ln a magnetohydrodynamic device for heating an ion-electron plasma to high Itemperatures, the Vcombination comprising:

(a) an annular outer electrode, (b) means creating a magnetic mirror eld in said outer electrode which ield has two regions of high `intensity iield separated by a region of lower inp tensity iield and which is symmetrical about a longitudinal 'axis through` said outer electrode,

(c) .a center electrode extending into said mirror substantially at said axis thereof,

(d) at least one annular field electrode encircling said axis of said magnetic iield at a position intermediate between said center electrode and said outer electrode and extending a small distance into said mirror field,

(e) means introducing a gas into the region of said mirror ield, v

(f) a high voltage power supply having a positive voltage terminal connected to both said outerelectrode :and `said center electrode and having a negative voltage terminal connected to said tieldrelectrode, and

(g) means for hermetically sealing and evacuating the region of said mirror field,

i'ield 4. In magnetohydrodynamic apparatus for generating and heating a plasma, the combination comprising:

(a) a cylindrical electrically conductive outer electrode,

(b) magnetic eld producing means disposed adjacent said outer electrode andprovi-ding a magnetic mirror containment region therein, Y

(c) a center electrode disposed at the axis of said outer electrode with at least a portion of said center electrede being ydisposed Within said containment region,

(d) at least one annular field electrode disposed coaxially Within said outer electrode and to one side of the central portion of said containment region and having a diameter intermediate between that of saidV outer electrode and said center electrode,

(e) an electrical power supply having a positive voltage terminal connected to both said' outer electrode and said center electrode and4 having a negative voltage terminal connected to said iield electrode,

(f) means for'hermetically sealing and evacuating said containment region, and

(g) means for emitting gas into said containment v region.

5. In apparatus for generating a high temperature ionelectron plasma, the combination comprising:

(a) a long ycylindrical outer electrode, 4v

(b) means producing a magnetic field hav-ing a plasma containment region within said outer electrode Which eld is symmetrical about the axis thereof,

(c) a long center electrode disposed along the axis of Y said outer electrode and extending into at least one end of said containment region,

- (d) at least one annular tield electrode disposed coaxially with respect to said center electrode at one end of said containment region and having a diameter intermediate between that of said outer electrode and that of said center electrode,

(e) a. rapidly opening valve disposed at the axis of said outer electrode ifor injecting gas into said containment region, :f

(f) an electrical power source having a positive potential terminal coupled to both said outer electrode and said center electrode and having a negative potential terminal coupled to said eld electrode, and

f (g) Ameans for hermetically sealing and evacuating said containment region.

6. In a magnetohydrodynamic device for ionizing and heating a gas, the combination comprising:

(a) a long cylindrical outer electrode,

(b) ia magnetic coil providing a magnetic mirror containment field within saidrouter electrode which iield is ksymmetrical about the axis of said outer electrode,

(c) atubular central electrode disposed Y'along said laxis of said outer electrode and extending into said containment field therein,

n (d) at least one annular iield electrode encircling said axis and having a diameter intermediate between that of said central electrode and that of said outer electrode, said field electrode being within a portion of mirror containment iield which is spaced axially from the central region thereof,

l -(e) an electrical power supply having a `positive terminal connected to vboth said outer electrode and said central electrode and having a negativeterminal connected to said eld electrode,

(f) means supplying gas to the region of said containment field through said central electrode, and

(g) means for maintaining a'substantial degree of vacuum in ythe region of said containment ieldjv 7. In apparatus for ionizing and heating a gas the combination comprising: A

v(a) a hermetically sealed cylindrical housing formed of electrically conductive material,V

(b) an annular magnetic coil disposed coaxially with respect to said housing and providing a plasma-conrtainment region therein of the magnetic mirror class,

(c) a` tubular cen-ter electrode disposed along the axis vof said housing and extending into at least one end of Y i said plasma containment region, (d) meansfor emitting gas into said plasma containment region,

y (e)v at least lone annu-lar held electrode disposed coaxially within said housinig in said containment region and at a positionspaced from the central poryclaimv 7 wherein saidgas emitting means (d) comprises `a rapidly opening valve disposed within said center electnode (c) and wherein said center electrode provided 'with atl least one aperture for emitting said gas, said aperture being said plasma containment region'.

y9. Gas ionizing and heating apparatus as described in claim'7 wherein said annular held electrode (e) provided with longitudinal slots at a pontion thereof outside said containment region of said magnetic mirror held whereby space charges formed around `said center electrode (c) may be dissipated.

10. |In ,appara-tus for creating and heating a plasma,

` the combination comprising:

(a) an annular outer electrode, (b) a magnetic held generating means producing a plasma containment magnetic mirror held within said outer electrode, the field being symmetricalabout a longitudinal axis Within said outer electrode and extending through said mirror held,

`(c.) Aa tublular center electrode disposed .along said axis within said outer electrode and extending through said mirror held,

(d) at least one annular held electrode disposed within said magnetic mirror field and being' spaced along said axis from the central region thereof, said held electrode encircling said center electrode andV ha'ving a diameter lintermediate between that of said f outer electrode and said center electrode,

(e)V a high voltage power supply applying a negative potential to said held electrode relative to that of said center and outer electrodes,

(f) means supplying gas to the region of said plasma y containment field, and Y(g) means maintaining a substantial degree of vacuum at said plasma containment region,

1.1.5111 a magnetohydrodynamic device lfor creating and heating a plasma, the combination comprising:

(a) a long cylindrical outer electrode,

(b): a magnet coil disposed coaxially with respect to said outer electrode and producing a magnetic mirror held there-in,

(c)A a tubular center electrode disposed alongthe axis of said housing and extending into said magnetic mirror held,

(d) a pair of annular eld electrodes disposed within said` outer electrode and encircling the axis thereof,

- said held electrodes being intermediate between said center electrode and said outer electrode and being spaced one on each side of the central region of said magnetic mirror held, Y y

(e) a high voltage power supply having a positive voltage terminal connected to both said center electrode andsaid outer electrode and having a negative voltlage terminal connected to said held electrodes,

(f) means 4for vemitting gas into saidmagnetic mirror held between said held electrodes, and (g) means for maintaining a substantial degree 0f vacuum'in the region of said mirror held. l2. A magnetohydrodynamic device as described in claim 1l wherein said eld electrodes are coaxial and intercept a common annular magnetic hux 'tube surface of said field. I j

13. In a magnetohydrodynamic device for creating and heating contra-rotating plasma bodies, ythe combination comprising: v

v(a) 4a long cylindrical outer electrode,

{(b) a central tubularelectrode disposed along the axis of said outer electrode. andhaving an aperture at an intermediate longitudinal position, v

(c) a pair of spaced apart annular field coils disposed coaxially around said outer electrode, one being on each side of said central electrode aperture, and being equally spaced therefrom,

(d) a magnet coil power supply coupled to said coils yto provide -for a similarly directed magnetic eld `through each coil whereby said coils form a magnetic mirror held centered on said aperture,

(e) a pair of annular held electrodes disposed coaxially with and intermediately between said outer velectrode and said central electrode'and having facingends spaced equally lon each side of said aperture,

(f) a high voltage power supply connected between said held electrodes and both said central electrode and said outer electrode,

(g) means for maintaining a substantial degree of vacuum in the region of said mirror field,

#(h) a rapidly opening valve disposed within said centrai electrode and having an outlet communicated with said aperture, and v (i) a gas supply coupled to said valve through said `central electrode.-

14. In a magnetohydrodynamic Ideviceforcreating and heating a contra-rotating plasma, the combination comprlsing: l

(a) a cylindrical conductive outer electrode having a central portion of enlarged diameter relative tov the terminal portions thereof,

(b) a pair of magnet coils disposed coaxially around said outer electrode with one on each side of said enlarged portion thereof,

(c) a magnet cur-rent supply coupled to said coils to provide a mirror type magnetic held within said 'enlarged portion of said outer electrode,

(d) a tubular center electrode disposedalong the axis 0f said outer electrode .and extending into said enlarged portion thereof. y

(e) an annular -iield electrode disposed coaxially with respect to said outer electrode and said centerY electrode and having a radius intermediate between that of said center and outer electrodes, said held electrode being within said mirror field and being spaced axially from the central region thereof, Y v

(f) an electrical power supply having a positive terminal connected to both said outer electrode and said center electrode and having a negative terminalV connected to said held electrode, (g) means for maintaining a vacuum within said outer electrode, and (h) a tast opening valve disposed withincsaid center' Yelectrode for emitting gas into said mirror held.

No vreferences cited. 

1. IN A MAGNETOHYDRODYNAMIC APPARATUS, THE COMBINATION COMPRISING: (A) AN ANNULAR OUTER ELECTRODE, (B) MEANS PROVIDING A MAGNETIC FIELD WITH SAID OUTER ELECTRODE WHICH FIELD IS SYMMETRIC ABOUT AN AXIS EXTENDING LONGITUDINALLY THROUGH SAID OUTER ELECTRODE AND WHICH FORMS A PLASMA TRAPPING REGION THEREIN, (C) A CENTRAL ELECTRODE DISPOSED WITHIN SAID OUTER ELECTRODE SUBSTANTIALLY AT SAID AXIS AND PROJECTING INTO SAID PLASMA TRAPPING REGION, (D) AN ANNULAR FIELD ELECTRODE DISPOSED WITHIN SAID OUTER ELECTRODE AND ENCIRCLING SAID AXIS IN SPACED APART RELATION TO SAID CENTRAL ELECTRODE AND SAID OUTER ELECTRODE, (E) A HIGH VOLTAGE SOURCE APPLYING A NEGATIVE POTENTIAL TO SAID FIELD ELECTRODE RELATIVE TO THAT OF SAID OUTER ELECTRODE AND SAID CENTRAL ELECTRODE, (F) MEANS FOR ADMITTING GAS TO SAID PLASMA TRAPPING REGION AND, (G) MEANS PROVIDING FOR A SUBSTANTIAL DEGREE OF VACUUM WITHIN SAID PLASMA TRAPPING REGION. 